1. Field of the Invention
Embodiments described herein generally relate to the field of method and apparatus for measuring the levels of Hormones, Neuro Transmitters, Bio Markers or the like.
2. Description of the Related Technology
Current techniques used to measure hormone levels are extracted from blood or saliva samples. Free cortisol levels can be measured from saliva samples that are proportional to blood level cortisol. Previous studies have shown an association between EEG characteristics and cortisol indicating subjects with high cortisol levels and low cortisol levels.
Cortisol is associated with various bodily systems such as stress, exercise, hunger, sleep and released in response to fear; it is a hormone that has many knock-on effects. Typically, cortisol levels are measured from the blood or from saliva samples (which are found to be significantly associated with blood cortisol levels). The principle challenge with the current method of measuring hormones is the delay in acquiring results from blood, saliva or urine samples. The current method of obtaining cortisol measure retrospective of the time of acquisition means any error in acquisition or storage would affect the extraction of cortisol levels measured from that sample, furthermore such errors may only be detected retrospectively resulting in repeated measures and testing with additional costs. Other issues are storage and transportation of these bio samples to and from the lab. These practical issues limit the use of measuring hormones in only absolute required cases where it could otherwise be used in the decision tree for improved diagnosis or research areas.
Quantitative EEG (qEEG) techniques include the computation of power and associated scalp topographic maps for given frequency bands. Such techniques have been used during the past three decades to illustrate, diagnose and investigate neuropsychological states such as depression, alcoholism, schizophrenia or cognitive functions such as attention disorders, memory and vastly used to diagnose epilepsy.
Previous studies have investigated the relationship, either between cortisol and a neuropsychological measure of stress or between the measure of stress (such as the behavioral inhibition scale) and the EEG activity. The findings of many of these studies hover around similar accounts of these relationships which repeatedly demonstrate a correlation between the amplitudes of the delta (1-3 Hz, also categorized as slow waves) and the beta frequency bands (15-25 Hz; considered to be fast wave activity). The term ‘coupling’ is used when amplitudes of both the beta and delta frequencies increase or decrease together, showing coherence. The beta-delta coupling reflects increased inter-regional cross-talk in the brain which indicates high or low stress-related indices of the behavioral inhibition and anxiety scale that in turn relates cortisol levels to the coupling activity of the delta and beta frequency since cortisol is also related to stress measured by the behavioral inhibition and anxiety scale. This was further supported by Schutter and Van Honk neuroendocrinology study (Schutter, D. J. L. G., Van Honk, J., 2004. Decoupling of midfrontal delta-beta oscillations after testosterone administration. Int. J. Psychophysiol. 53, 71-73) that demonstrated beta-delta decoupling after administering testosterone, an antagonist of cortisol, i.e. low cortisol levels is associated with a lack of beta-delta coupling; termed ‘decoupling’. Beta-delta decoupling is found in the subjects of the low cortisol group and beta-delta coupling in the high cortisol group. A more recent study by Van Peer et al (Van Peer, J. M., Roelofs. K., Spinhoven. P., 2008. Cortisol administration enhances the coupling of midfrontal delta and beta oscillations. Int. J. Psychophysiol. 67, 144-150) shows the direct effects of cortisol on the delta (1-4 Hz) and beta (14-33 Hz) frequency bands by administering different doses of an oral form of cortisol to participants and compared changes in their EEG pre and post cortisol administration. The finding revealed that increased dosage of cortisol resulted in beta-delta coupling at the mid-frontal region (FZ) further supporting the relationship between beta-delta activity of the EEG spectrum and cortisol. These studies demonstrate a close relationship with EEG activity and hormones, indicating the potential to use the EEG data to predict measures of hormones levels.